Using your phone before bed is linked to worse sleep and weaker focus in university students, according to a study published in Scientific Reports on May 14, 2026. Students who spent more than 60 minutes on their phones with the lights on had 2.4 to 3.7 times higher odds of poor sleep. If you are studying for exams on four or five hours of broken sleep, this is worth five minutes of your time.
Key Facts
- Source: Scientific Reports, published May 14, 2026.
- The final sample was 187 university students, down from 263 initial participants.
- On average, students used their phones for 75.78 minutes with the light on and 38.50 minutes with the light off before sleeping.
- About 70% of participants reported poor sleep quality.
- Using a phone for more than 60 minutes with the lights on, or more than 30 minutes with the lights off, was linked to 2.4 to 3.7 times higher odds of poor sleep.
- Longer pre-bed phone use was also linked to lower concentration scores and slower reaction times.
What the Research Found
The study found that more phone time before bed went along with worse sleep, lower concentration and slower reactions. The students in the sample were not unusual: they scrolled for well over an hour on average, and roughly seven in ten reported poor sleep.
The authors link the pattern to blue-light exposure, which can suppress melatonin, the hormone that helps signal bedtime. Their results show an association, so they do not prove that phones alone caused every bad night. Still, the direction is consistent across sleep, attention and reaction time.
Lights on versus lights off
Both habits showed up in the data. The risk threshold was more than 60 minutes with the lights on, or more than 30 minutes with the lights off. Scrolling in the dark under the blanket is not a safer option.
What This Means for Students
For students, the practical message is simple: the last hour before sleep matters for tomorrow’s focus. Reaction time and concentration are what you lean on during a long exam paper or a problem-solving session. A late-night scroll can quietly eat into both.
Earlier research points the same way. A Norwegian study of nearly 40,000 university students, reported by the American Academy of Sleep Medicine’s Sleep Education site, tied each extra hour of screen time after going to bed to a 59% higher chance of insomnia symptoms and about 24 fewer minutes of sleep.
How to Cut Phone Use Before Bed
You do not need a perfect routine. Start with one or two changes and keep them for a week. Sleep Education suggests the following:
- Power down electronics at least 30 to 60 minutes before bed.
- Charge your phone in another room and use an alarm clock instead.
- Replace scrolling with something calming, such as reading, journaling or a warm shower.
- Keep a consistent sleep and wake time, even on weekends.
- If the phone has to stay nearby, turn off notifications.
If you use AI study apps late at night, treat them like any other screen. Finish the session, close the app, and let your revision settle overnight.
FAQs
Q. How long before bed should students stop using their phones?
Ans. The American Academy of Sleep Medicine’s Sleep Education site advises powering down electronics at least 30 to 60 minutes before bed. The 2026 Scientific Reports study found risk rising once use passed 60 minutes with lights on or 30 minutes with lights off.
Q. Does using a phone in the dark make it safer for sleep?
Ans. No. In the study, more than 30 minutes of phone use with the lights off was still linked to higher odds of poor sleep. Dim light does not remove the effect.
Q. Can phone use before bed affect exam performance?
Ans. The study linked longer pre-bed phone use to lower concentration and slower reaction times. It did not measure exam marks, so the safest reading is that poorer sleep and focus can make studying harder.
Q. Does this study prove phones cause poor sleep?
Ans. No. It reports associations between phone use, sleep and performance. The authors point to melatonin suppression from blue light as a likely mechanism.
Q. What if poor sleep continues even after I cut screen time?
Ans. Persistent sleep trouble or low mood is worth discussing with a doctor, a campus or school counsellor, or a trusted adult. This article is general information, not medical advice.
Next Steps
Pick one change tonight: put the phone on charge outside your bedroom, or set a 30-minute screen cutoff. Try it for a week and notice how your focus feels during morning study. Check back for more student sleep, study and wellbeing updates.